Resilient contacts for rotary switch having an intermediate position of unstable equilibrium

ABSTRACT

A switch includes a base member with first and second switch contact elements secured thereto and projecting therefrom. At least one of the elements is movable from a first position in which the elements are disengaged to a second position in which they are engaged. In both positions the elements cross each other when viewed from one angle but are on opposite sides of each other in the two different positions. At least the movable contact element is resilient and passes through a position of unstable equilibrium when moved between the two positions. When attempting to return to the first position after having been moved therefrom through the intermediate position, the movable contact element engages the other contact element.

United States Patent Inventor Frits L. Lyvang Wallenstein, Ontario,Canada Appl. No. 756,793 Filed Sept. 3, 1968 Patented Feb. 16, 1971Assignee Electrohome Limited Kitchener, Ontario, Canada RESILIENTCONTACTS FOR ROTARY SWITCH HAVING AN INTERMEDIATE POSITION OF (B1), 159(A), 155, 155.1, 67 c), 63

[56] References Cited FOREIGN PATENTS 319,193 1/1919 Germany 200/63810,597 6/1951 Germany 200/166(B1) Primary Examiner-Robert K. SchaeferAssistant Examiner-Robert A. Vanderhye AttorneyPeter W. McBurneyABSTRACT: A switch includes a base member with first and second switchcontact elements secured thereto and projecting therefrom. At least oneof the elements is movable from a first position in which the elementsare disengaged to a second position in which they are engaged. In bothpositions the elements cross each other when viewed from one angle butare on opposite sides of each other in the two different positions. Atleast the movable contact element is resilient and passes through aposition of unstable equilibrium when moved between the two positions.When attempting to return to the first position after having been movedtherefrom through the intermediate position, the movable contact elementengages the other contact element.

RESILIENT CONTACTS FOR ROTARY SWITCH HAVING AN INTERMEDIATE POSITION OFUNSTABLE EQUILIBRIUM The present invention relates to electricalswitches, more especially to electrical switches suitable for use in lowpower applications.

The switch comprises a pair of switch contact elements secured to andprojecting from a base member. At least one of the contact elements, andgenerally both, is resilient and is movable between positions where thecontact elements are disengaged from each other and where the contactelements are engaged with each other, the contact or contacts passingthrough a position of unstable equilibrium during movement between theaforesaid positions. The contact elements are so oriented in these twopositions that they cross each other in the two positions on oppositesides of each other. At least one contact element, and generally both,is deflected during movement from the position where the elements do notengage each other to the position ofunstable equilibrium and attempts toreturn to the original position by dissipation of the spring energystored within the contact element by this movement. When thecontact'element is moved through the position of unstable equilibrium,it-still' attempts to return to its original position, but it isprevented from doing so by engagement with the other contact element. t

The invention now will be further described by way of example, withreference to the accompanying drawings, in which: l

FIG. 1 is a side elevation, partly in section, of one embodiment of theinvention with the contact elements in nontouching relationship; 7

FIG. 2 is aside elevation, partly in section, of the switch of FIG. Iwith the contact elements in touching relationship;

FIG. 3 is a section taken along line 3-3 of FIG. 1;

FIG. 4 is a section similar to that of FIG. 3 but with the contactelements rotated to a first intermediate position;

FIG. 5 is a section similar to that of FIG. 3 but with the contactelements rotated to a second intermediate position; FIG. 6 is a sectiontaken along line 6-6 of FIG. 2; and

FIG. 7 is a closeup of an element of the switch of FIGS. 1 and 2.

In the drawings, a switch 10 consists of a base 12 located in asupporting frame 14 having a top wall 16. Mounted in base 12 are twocontact elements 18 20 consisting of resilient, upwardly projectingwires which are inclined to the base and cross each other at a crossoverpoint 22. Contact elements 18, 20 are connected on the underside of base12 to printed circuit conductors 24. At their upper. ends elementsl8, 20are slidably engaged in passages 26, 28 respectively formed in a knob30. The knob 30 is mounted .for rotational movement in a recess formedby the top wall 16 of the frame '14 and by a bracket member 32 whichsandwiches a portion 34 of en-. larged diameter of the knob 30 betweenit and thetop wall 16.

In operation, the switch is in an.off position in FIGS. 1 and 3 sincethe elements 18, 20 do not contact each'other at 22, and therefore nocircuit is completed between conductors 24. In the position shown inFIGS. I and 3 the elements 18 and 20 are relaxed and have noresidual'spring tension therein. As

, knob 30 is rotated in a clockwise direction, as indicated by thearrows in FIGS. 4 and 5, the elements 18 and 20 are deflected and rideup in passages 26, 28.'Spring energy is stored in the elements by thismovement. Considering the position of the elements 18, 20shown in FIG.4, if the knob 30 is released, the spring energy will be released, andthe elements will again assume their relative location as shownin FIG.3. Considering the position of the elements 18, 20 shown in FIG. 5, ifthe knob is released, each of the elements 18, 20 will attempt to assumethe position it held in the arrangement of FIG. 3 by release of thespring energy. It is impossible for both elements to assume thatposition, and, instead, the elements engage each other at the crossoverpoint 22, as seen in FIGS. 2 and 6, thereby completing a circuit betweenconductors 24. There is residual spring energy in the elements 18, 20when they are in the position of FIG. 6, since each has failed to assumethe at rest position of FIG. 3, and this spring energy holds theelements in engagement with each other at 22. The position illustratedin FIGS. 6 and 2 thus represents the on" position of the switch.

To return the switch to its off position, i.e., the position shown inFIG. 3, the knob 30 is rotated in an anticlockwise direction. If theknob is released with the elements 18, 20 in the position shown in FIG.5, the elements will return to the position shown in FIG. 6 bydissipation of a part of the spring energy; whereas, if the knob isrelease with the elements 18, 20 in the position shown in FIG. 4, theelements will assume the ofi position shown in FIG. 3 by dissipation ofall the spring energy stored therein due to the deflection of theelements.

It will be seen from a comparison of FIGS. 1 and 2 that when the switchis in the off position, i.e., the position of FIG. 1, the element 20 isnearer to the far side of element 18 than to the near side thereof atthe crossover point 22, whereas, when the switch is in the fon"position, the element 20 engages the near side of element 18 at thecrossover point 22.

Thus, up to a particular point from the off position, release of theknob after rotation towards that point will release the spring energy insuch a manner that the contact elements will assumethe off positionshown in FIG. 3, but release of the knob after rotation beyond thatpoint will release the spring energyin such amanner that the contactelements will assume the on position shown in FIG. 6. If the knob isrotated to exactly that point, release thereof will have no effect,since the contact elements at that point will be in a state of unstableequilibrium, but the elements will over-toggle to one position or theother by movement thereof from that point.

It will be seen from the foregoing that, while contact ele-'- ments l8and 20 always will attempt to return to the position of FIG. 3 whendisplaced therefrom, once the elements have been displaced to theposition thereof shown in FIG. 5, they are unable to spring back in acounterclockwise direction to 'the position of FIG. 3. Consequently,they attempt to spring to the position of FIG. 3 in a clockwisedirection but are prevented from reaching the FIG. 3 position in thisdirection because of interfering with each other.

It is not essential to the invention that both contact elements be movedby knob 30. Indeed, one of the contact elements may remain perfectlystationary while the other is moved around it. v

A switch embodying the present invention is simple in both constructionand operation. Having built-in spring action, the operation of theswitch is both positive and reliable. The fact that a contact elementserves both an electrical function as well as a spring function ratherthan having two separate members performing these individual functionsalso is of importance.

In a modified embodiment of the invention openings 26 and 28 may betapered, being wider at the bottom than at the top.

. With such an arrangement elements 18 and 20 will be able to movewithin knob 30 without sliding up and down in the so modified passages26 and 28.

In another embodiment of the invention one of elements 18 and 20 mayextend vertically from base 12 and may have it its free end disposed ina centrally located opening in knob 30. In such an embodiment thiselement will support knob 30 making bracket member 32 unnecessary.

Other embodiments of this invention are possible within the scope of theappended claims.

I claim:

1. A switch comprising: a base member; first and second switch contactelements secured to said base member andprojection therefrom; at leastone of said contact elements being movable from a first position inwhich said contact elements are disengaged from each other to a secondposition in which respect to each other that said contact elements crosseach other when viewed from one angle with said one contact elementbeing closer to one side of said second contact element .than to theopposite side of said second contact element; said contact element; atleast said one contact element being resilient; and means for movingsaid one contact element between said first and second positions throughan intermediate position of unstable equilibrium; said one contactelement being deflected during movement thereof from said first positionto said intermediate position; said one contact element alwaysattempting to return to said first position by dissipation of springenergy stored in said one contact element during movement thereof fromsaid first position; said one contact element when attempting to returnto said first position after movement of said one contact element fromsaid first position through said intermediate position assuming saidsecond position by reason of engagement with said second contactelement. p

2. The switch of claim 1 wherein both said first and second contactelements are resilient.

3. The switch of claim 2 wherein both said contact elements areconnected to said moving means and are movable from said first positionto said second position, both said contact elements are deflected duringmovement thereof from said first position to said intermediate-position,both said contact elements always attempt to return to said firstposition by dissipation of spring energy stored therein during movementfrom said first position, and both said contact elements engage oneanother in said second position as they attempt to return to said firstposition after movement of both said contact elements from said firstposition through said intermediate position.

4. The switch of claim I wherein said first and second contact elementsare each resilient wires upstanding from, said base member, said wiresbeing inclined towards and crossing each other at a point intermediatetheir length when viewed from said one angle. I

5. The switch of claim 4 wherein said means for moving said one contactelement is a knob engaging the free ends of said wires, said knob beingadapted for rotational movement about an axis substantiallyperpendicular to said base member.

6. The switch of claim 5 wherein said free ends of said wires areslidable in said knob.

7. The switch of claim 3 wherein said first and second contact elementsare each resilient wires upstanding from said base member, said wiresbeing inclined towards and crossing each other at a point intermediatetheir length when viewed from said one angle.

8. The switch of claim 7 wherein said means for moving said one contactelement is a knob engaging the free ends of said wires, said knob beingadapted for rotational movement about an axis substantiallyperpendicular to said base member.

9. The switch of claim 8 wherein said free ends of said wires areslidable in said knob.

1. A switch comprising: a base member; first and second switch contactelements secured to said base member and projection therefrom; at leastone of said contact elements being movable from a first position inwhich said contact elements are disengaged from each other to a secondposition in which said contact elements are engaged with each other;said contact elements in said first position being so oriented withrespect to each other that said contact elements cross each other whenviewed from one angle with said one contact element being closer to oneside of said second contact element than to the opposite side of saidsecond contact element; said contact elements in said second positionbeing so oriented with respect to each other that said contact elementscross each other when viewed from said one angle with said one contactelement engaging said opposite side of said second contact element; atleast said one contact element being resilient; and means for movingsaid one contact element between said first and second positions throughan intermediate position of unstable equilibrium; said one contactelement being deflected during movement thereof from said first positionto said intermediate position; said one contact element alwaysattempting to return to said first position by dissipation of springenergy stored in said one contact element during movement thereof fromsaid first position; said one contact element when attempting to returnto said first position after movement of said one contact element fromsaid first position through said intermediate position assuming saidsecond position by reason of engagement with said second contactelement.
 2. The switch of claim 1 wherein both said first and secondcontact elements are resilient.
 3. The switch of claim 2 wherein bothsaid contact elements are connected to said moving means and are movablefrom said first position to said second position, both said contactelements are deflected during movement thereof from said first positionto said intermediate position, both said contact elements always attemptto return to said first position by dissipation of spring energy storedtherein during movement from said first position, and both said contactelements engage one another in said second position as they attempt toreturn to said first position after movement of both said contactelements from said first position through said intermediate position. 4.The switch of claim 1 wherein said first and second contact elements areeach resilient wires upstanding from said base member, said wires beinginclined towards and crossing each other at a point intermediate theirlength when viewed from said one angle.
 5. The switch of claim 4 whereinsaid means for moving said one contact element is a knob engaging thefree ends of said wires, said knob being adapted for rotational movementabout an axis substantially perpendiculAr to said base member.
 6. Theswitch of claim 5 wherein said free ends of said wires are slidable insaid knob.
 7. The switch of claim 3 wherein said first and secondcontact elements are each resilient wires upstanding from said basemember, said wires being inclined towards and crossing each other at apoint intermediate their length when viewed from said one angle.
 8. Theswitch of claim 7 wherein said means for moving said one contact elementis a knob engaging the free ends of said wires, said knob being adaptedfor rotational movement about an axis substantially perpendicular tosaid base member.
 9. The switch of claim 8 wherein said free ends ofsaid wires are slidable in said knob.